However, in the remaining five cases, in contrast to their associated H3F3AG34W-mutant giant cell tumor, the sarcoma lacked the H3F3A G34W mutation, either entirely or sub-clonally in the samples tested.
The identification of H3F3A mutation in giant cell tumour of the clivus and the histological diagnostic algorithm of other clival lesions permit the differential diagnosis in this location.
H3 histone family member 3A (H3F3A) (G34W/V/R/L) mutations are present in the majority of giant cell tumors (GCTs) of bone and H3 histone family member 3B (H3F3B) (K36M) mutations are present in nearly all chondroblastomas, but are absent in histologic mimics.
Point mutations of the H3F3A gene (coding for a histone H3.3 protein) at the Gly34 codon, mostly G34W resulting from a GGG>TGG nucleotide change, have recently been identified in a vast majority of giant cell tumors of bone.
H3F3A mutation in giant cell tumour of the bone is detected by immunohistochemistry using a monoclonal antibody against the G34W mutated site of the histone H3.3 variant.